Joomla is a CMS platform similar to Wordpress and Durpal and while there are many CMS platforms those are some of the biggest players. Wordpress became very popular probably because they host blogs for free on there site making it attractive for newbies and a breading ground for future Wordpress designers. While Joomla probably became more popular filling the many different needs of business back when Wordpress was mostly just a blogging platform. Nowadays both have made a lot of progress and are more similar to each other in terms of flexibility than when they started.
Today they are both great, I focus on Joomla because I think its easier to use and therefore will be easier for my clients to use. I still think its a better platform for business use. It also has many extensions that I like and that I think would be valuable to my clients their sites and there search rankings.
CMS (content management system), is database driven which makes editing the website very fast. In ancient times during a period known as the dial up days of internet using software like Microsoft FrontPage it would take a very long time to build a website because every menu link on every page had to be manually updated and created, if you wanted objects on every page you had to manually add them there. Now stuff like menu buttons, articles, and side modules are all stored separately in the database, then Joomla spits it all out on the front-end as a webpage. In a CMS site content areas that are HTML will be easy to edit using a WYSIWYG editor (What you see is what you get) similar to Microsoft Word or your Email editor so updating an article text or adding an image will already be familiar grounds for most users. With CMS if you change the home page menu button to point at a different article via the backend administrator area, then that link updates on all your pages. Thanks to CMS Websites today are easier and faster to build just like computers in general are faster and easier to use.
So what is Responsive website design? Responsive design is something that is added to the Template to make sure the website will fit any size screen like a small mobile device. So before we dig into responsive website design it makes sense to talk about templates first. Popular CMS platforms like WordPress and Joomla use templates. You might be familiar with a metal, wood or a pattern template or one of those plastic shaped stencils for drawing when you were a kid. Just like a round stencil can help you draw a perfect circle then later you might make a face or wheel or something else out of that circle so to a web template helps to kick start your website. Similarly picture frames come in all shapes sizes and colors some have several boxes to put smaller pictures, some have a big box with a few smaller boxes, likewise CMS templates have grid structures to them, some more flexible and more complex than others. Since all Joomla and Wordpress sites use templates if you have a Joomla/Wordpress web designer saying "I don't use templates" I would question them. If they don't install a custom or premium template they could use the default free included template which you defiantly don't want that. Now some web designers claim to build their own templates from scratch, and while that may sound impressive it really depends on the quality of the template. There is templating software available that can help a newbie to poop out custom templates all day long, but that is not impressive if they are custom pieces of shipwreck. I can build a picture frame from scratch with a few pieces of wood and nails but that does not mean I would want to put it on my wall. In contrast there are premium template sellers/companies/clubs who make templates from scratch for a living, some of the better clubs have entire teams developing a custom template for months, thease templates are often sold over and over again from $5-$100 or more. Both newbies and professional website designers buy them because they are much better than the free one that comes with the CMS platform. So when someone says "I can build a template from scratch" it is wize to consider the quality of the template they are building, but if you don't know css, php, html, or other web markup then you should probably not be deciding about the template quality. Just like the cover of a book does not always represent the quality of the story inside so to just because a template looks great on a demo site does not mean that it is a good template. I have seen alot of real estate templates for example that would seem to give you the ability to add property's for sale and allow customers to sort by all kinds of criteria but in actual the interface is just an image or non functioning fields, the template included no such real estate software and is pretty much just like any other basic template even though it was presented as a real estate template. Buying a template from a premium template developer with a good reputation who probably had a team working on it for months is sure to have a lot more bells and whistles than the $5 one some newbie spit out using a templating software. Even if they both look great on the front-end there is a lot of stuff going on behind the scenes (or not going on) that you cant always see in the demo. For example Joomlaxtc is a premium template club that has in each of their templates a template management area where you can easy change the colors of the site or logo or logo width and lots of other stuff without needing to know css or hack the css files of the template. I have seen other template sellers that have no custom options for easy site edits in the backed. Weather you are building the site yourself or you hire a web designer a well built premium template can shave several or more hours off a build so either way if time is money you save money. While any template can be modified/customized and the final site might look much different than the original template you will save even more time by finding a template that has features you already would like in the final site. A quality template can be a turbo charged quick start to your overall web development, the closer the template design is to what you are looking for the more time will be left to customize and add design elements to your website. So not only do you need a template for your Joomla site, since the web is constantly evolving you want the most recent and premium one you can find.
Ok, so now that you know about Joomla, CMS, and Templates you can understand responsive templates which is recently becoming massively popular. In the way back years of long ago when smart phones just started becoming popular if you wanted a website to look good on a smaller screen you had to develop either a separate website or separate css style sheets, it was a lot of extra work and expense to make mobile ready sites. Now we have responsive design templates which are made so that the grid system in the template will shrink or expand based on the screen size of the device so if you have a mobile phone you might see one column or if you have a TV or large monitor display you might see 4 or more columns. Images, Video, Text areas can all be made to shrink and expand and reposition themselves for different screen sizes. With Smart phones and tablets becoming more popular, new devices always being developed and smaller sizes of internet viewing, responsive templates are becoming more important. Nowadays I am recommending my clients use a responsive template.